Nested packaging trays produced by a rotary pulp molding machine having different sets of molding dies

ABSTRACT

Apparatus for producing stack of nested articles comprises first and second sets of plural molding dies mounted in alternating fashion for shifting motion along an endless path past an article molding station. The first and second sets of plural molding dies have anti-jamming steps which are different in location from one another. Mechanical stacker places molded articles in nested fashion one above other in order articles are delivered to stacker. Article handling structure transfers articles from molding dies to stacker in same order articles are formed. Mechanical stacker produces stack of nested articles with every even numbered article therein having been molded on first set of molding dies and every odd numbered article having been molded on second set of molding dies.

Apnl 4, 1972 w, HATCH NESTED PACKAGING TRAYS PRODUCED BY A ROTARY PULPMOLDING MACHINE HAVING DIFFERENT SETS OF HOLDING DIES Filed Sept 29 1969 United States Patent M US. Cl. 162-391 2 Claims ABSTRACT OF THE DISCLOSURE Apparatus for producing stack of nested articles comprises first and second sets of plural molding dies mounted in alternating fashion for shifting motion along an endless path past an article molding station. The first and second sets of plural molding dies have anti-jamming steps which are different in location from one another. Mechanical stacker places molded articles in nested fashion one above other in order articles are delivered to stacker. Article handling structure transfers articles from molding dies to stacker in same'order articles are formed. Mechanical stacker produces stack of nested articles with everyueven numbered article therein having been molded on first set of molding dies and every odd numbered article having been molded on second set of molding dies.

The present invention relates to nested articles, and more particularly to a stack of nested articles wherein each of the articles comprising the stack has substantially the same general overall configuration and adjacent articles in the stack have minor design differences not incompatible with the nestability of thearticles. Apparatus and method are also provided for producing a nested stack of molded articles as aforesaid.

. As is well known, molded pulp products produced by conventional pulp molding techniques are formed upon open-face suction dies. The forming dies must be designed to have sufficient draft or flare to facilitate removal of the damp products after a predetermined thickness of pulp is deposited upon the dies. The outwardly inclined side walls thus permit nested stacking of the finished articles for storage or shipment. Usually the stack is com pressed to minimize its height and the nested products are so firmly wedged together it is, thereafter, extremely difficult to disengage the products from each other without tearing or otherwise deforming them. Solid de-nesting lugs prevent such jamming or wedging of the trays and facilitate their release from one another, and have recently gained popularity in the molded pulp art. Hollow antijamming steps have been in use for a longer time than solid lugs, however, hollow steps tend to nest one within the other to thereby destroy their intended spacing function unless each step includes a true vertical segment that engages a corresponding vertical segment of the step of the article next thereabove in the vertical stack to thereby support and space adjacent articles in the stack a predetermined distance from one another, known as the stacking interval. Vertical side walls are expensive and difiicult to provide because removal of the damp articles from the molding dies is hampered by the absence of a draft angle and mold construction and molding procedures are critical when article designs require vertical sections.

3,654,076 Patented Apr. 4, 1972 Another object of the present invention is to provide a stack of nested articles wherein the article bottoms are adequately spaced from one another to prevent jamming and individual end articles are easily disengaged singly from the balance of the nested stack.

Another object of the present invention is to provide apparatus and method for producing a stack of nested articles wherein adjacent articles of the stack have minor design differences.

SUMMARY OF THE INVENTION In accordance with the present invention, a stack of nested articles comprises at least a pair of articles, each having substantially the same general overall configuration except for minor design differences not incompatible with the nestability of the articles. Specifically, each article of the nested stack includes a bottom wall and an upwardly and outwardly extending side wall having a continuous peripheral rim. Both the peripheral rim and bottom wall of each article of the stack may be substantially planar.

In a preferred embodiment of the present invention, the minor design diiferences between the articles of the stack comprise upwardly extending hollow anti-jamming steps formed in the bottom wall of each article and arranged so that the steps of each article are out of vertical alignment with the steps of the immediately adjacent articles in the stack. Every even numbered article in the stack may have a similar arrangement of hollow anti-jamming steps different from the arrangement of the anti-jamming steps of the odd numbered articles in the stack.

Preferably, the hollow anti-jamming steps of each article of the nested stack are located in the area where the bottom wall is connected to the upwardly and outwardly extending side wall. Each article may have a substantially rectangular outline and four anti-jamming steps, one step formed in the midportion of each of the four sides of the article. Moreover, the steps associated with the short sides of the article may be disposed on opposite sides of the longitudinal centerline of the article, and the steps associated with the long sides can be disposed on opposite sides of the transverse centerline of the article.

The apparatus of the present invention for producing a stack of nested articles comprises first and second sets of plural open-face molding dies supported and arranged in alternating fashion for shifting motion along an endless path past an article molding station comprising a source of aqueous pulp slurry. Suction connected to the molding dies draws pulp onto the dies as they pass through the source of aqueous pulp slurry. A mechanical stacker functions to stack molded articles in nested fashion one above the other in the order the articles are delivered to the stacker. The present apparatus also includes article handling structure for transferring molding articles from the first and second sets of molding dies to the stacker in the same order the articles are formed. The stacker produces a nested stack with every even numbered article therein having been molded on the first set of molding dies and the odd numbered articles having beenmolded on the second set of molding dies. j

Preferably, the article handling structure for transferring articles to the stacker includes first and second. sets Accordingly, it is an object ofthe present invention to provide a stack of nested articles wherein each article of the stack has substantially the same general overall configuration. and adjacent articles have minor design differences not incompatible with the nestability of the articles.

The present invention also includes a method for producing a vertical stack of nested articles. The method of the instant invention comprises the steps of continuously molding different but substantially nestable articles one after the other in predetermined sequence. Next, the molded articles are handled one after the other in the same predetermined sequence to form a nested stack by placing each article directly above the precedent article of the sequence.

BRIEF DESCRIPTION OF THE DRAWING Novel features and advantages of the present invention in addition to those mentioned above will become apparent to one skilled in the art from a reading of the following detailed description in conjunction with the accompanying drawing wherein:

FIG. 1 is a semi-schematic side elevational view of a molding machine for producing a vertical stack of nested packaging trays according to the present invention;

FIG. 2 is a side elevational view of a stack of nested packaging trays according to the present invention;

FIG. 3 is a top plan view of the stack shown in FIG. 2 with portions of the top tray broken away; and

FIG. 4 is a fragmentary sectional view taken on line 44 of FIG. 3.

DETAILED DESCRIPTION OF THE INVENTION Referring in more particularity to the drawing, FIG. lillustrates a molding machine for producing molded pulp products, such as trays 12, 14. The individual trays 12, 14 produced by the molding machinery are ultimately nested one within the other in alternating fashion to produce a vertical stack 16.

The stack 16 of nested packaging trays according to the present invention is shown best in FIGS. 2, 3 and 4. Each tray comprises a planar bottom wall 18 with an upwardly and outwardly extending side wall 20 having a rim 21 occupying a substantially fiat plane. Upwardly extending hollow anti-jamming steps 22 are formed in the bottom wall 18 in the area where the bottom Wall is connected to the upwardly and outwardly extending side wall 20. Exery other tray in the vertical stack 16 has a similar arrangement of hollow anti-jamming steps diiferent from the remaining trays of the stack. As shown in FIG. 3, the hollow steps 22 in the trays 12 are out of vertical alignment with the steps of the other trays 14. Since the trays 12 in the vertical stack 16 have a similar step arrangement different from the trays 14, the bottom wall of each tray in the stack is supported by the steps of the tray directly therebelow in the stack. The hollow steps function to space adjacent trays a predetermined distance from each other to prevent jamming and wedging of the sidewalls of the trays when the trays are nested one within the other to form the vertical stack 16. As mentioned above, prevention of jamming and wedging enables individual end trays to be easily disengaged singly from the balance of the stack without mutilating the trays.

The hollow de-nesting steps 22 of each tray are disposed in the corner area of the tray where the bottom wall 18 is connected to the upwardly and outwardly extending side wall 20. Preferably, each tray has a substantially rectangular outline and four de-nesting steps, one step formed in the mid-portion of each of the four sides of the tray. Obviously, other step locations are possible within the scope of this invention the only criterion being that the step location be different from that of he immediaely adjacent trays. In the embodiment of the invention illustrated in FIGS. 2-4, the hollow steps 22 associated with the short sides of the trays 12 are disposed on opposite sides of the longitudinal centerline of the trays, and the steps associated with the long sides are disposed on opposite sides of the transverse centerline of the trays. The hollow steps formed in the trays 14 are also disposed on opposite sides of the tray centerlines but on centerline sides different from the orientation in the trays 12.

The hollow nature and particular configuration of the anti-jamming steps 22 of each tray provide a group of flat plateaus upon which is supported the bottom wall of the tray directly thereabove in the nested stack. The selected elevation of the steps determines the spacing or stacking interval between adjacent trays in the stack. The elevation of the steps is selected with reference to the draft angle of the side walls so as to avoid jamming or wedging of the trays and effect release after compression of the entire stack during shipping.

As explained above, FIG. 1 illustrates machinery, according to the present invention, for producing the vertical stack 16 of nested packaging trays 12, 14. The molding machine 10 comprises a molding die turret 30 that carries in alternating fashion first and second sets of plural openface suction molding dies 32, 34. Every other molding die, such as the dies 32, is configured to produce the trays 12 while the remaining dies 34 are configured to produce the trays 14. Thus, the single molding die turret 30 pro duces two individual tray constructions each having a similar bottom wall 18 and side wall 20 but different arrangements of hollow anti-jamming steps 22 out of vertical alignment with each other when the trays are nested one within the other in alternating fashion. The turret 30 is mounted for continuous rotary motion about a horizontal axis 36. Molding die support elements 38 are provided for securing the open-face suction dies to the molding machine, as shown in FIG. 1.

The first and second sets of molding dies pass into and through a tank or vat 40 containing aqueous pulp slurry 42. The molding die support elements are connected to a central hub 44 by means of a spoke-like conduit arrangement 46. As is well known, suitable stufiing box porting arrangements are provided at the axial ends of the turret 30 whereby the various molding dies 32, 34 mounted on the support elements 38 may be ported to a source of suction, to atmosphere, or to a source of pressurized air at predetermined peripheral locations along their orbital path of travel. Accordingly, as each molding die 32, 34 passes a given point in its orbital path the supply of suction or pressure is controlled so as to suck the fibrous pulp onto the dies as they travel through the tank 40 and to blow the formed trays off the dies when they are transferred to a tangentially positioned transfer die turret 50.

The transfer die turret 50 is in many respects similar to the molding die turret 30. First and second sets 52, 54 of plural transfer dies are alternately arranged around the periphery of the transfer die turret. The individual dies are connected to transfer die support elements 56 which in turn are connected to a spoke-like conduit arrangement 58. The spokes of the conduit arrangement are connected to a central hub 60' which in turn is connected to a suitable stuffing box porting arrangement. The transfer dies are ported to a source of suction, to atmosphere, or to a source of pressurized air at predetermined locations along their orbital path of travel. As each transfer die 52, 54 passes a given point in its orbital path the supply of suction or pressure is controlled to perform the desired article handling maneuver. For instance, at the transfer station 62, located on a line which connects the axes of rotation of the turrets 30 and 50, the molded trays are transferred from the first and second sets of molding dies 32, 34 to the first and second sets of transfer dies 52, 54. The trays are held, for instance, on the molding dies of the turret 30 by suction and, when the station 62 is reached the connection with the source of suction is closed and the connection with the source of pressure is opened to blow the trays off the molding dies. At this point the mating transfer dies 52, 54 on the turret 50 are connected with the source of suction to insure pick-up of the damp molded articles.

Additionally, as is well known with this type of machinery, the turrets 30 and 50 are driven continuously in unison by means of large bull gears or other mechanical arrangements to insure that the surface speeds of the two turrets coincide. This permits a shifting of trays from the molding dies of turret 30 to the transfer dies of turret 50 with smooth continuous motion.

The damp trays 12, 14 are blown from the first and second sets of transfer dies 52, 54 onto a continuously moving belt conveyor 64. The transfer of the trays 12, 14 occurs at station 66, shown in 'FIG. 1. When the individual transfer dies approach station 66 the suction utilized to assist in transferring the trays from the molding dies to the transfer dies is cut off and the connection with the source of pressure is opened to blow the trays off the transfer dies onto the belt conveyor 64. The damp articles are then conveyed into and through a drying chamber 68 and then to a mechanical stacker 70. The stacker operates to form the vertical stack 16 by placing trays 12, 14 in alternating fashion onto the stack. As mentioned above, every other tray in the stack has a similar arrangement of hollow anti-jamming steps which is different from the remaining immediately adjacent trays of the stack. Also, the hollow steps of adjacent trays in the stack are out of vertical alignment with each other to space adjacent trays a predetermined distance from one another to prevent jamming.

While the particular trays with anti-jamming steps described above constitutes a preferred form of the present invention, the inventive concept is considerably broader and embraces minor design differences other than antijamming steps so long as the minor design differences are not incompatible with the ability of the articles to nest one within the other. For instance, my invention includes a stack of articles comprising at least a pair of articles each having substantially the same overall shape, size and configuration but the articles of a pair differing by one having either scalloped-out portions or outwardly flaring flanges on only the side walls and the other having corresponding portions or flanges on only the end walls for cooperation with de-stacking machinery; or the articles of a pair differing by one having waflle ridge embossing on its bottom to serve as the lower portion of a two-part container and the other having decorative embossing on its bottom to serve after being inverted as the cover portion of a two-part container; or the articles of a pair differing by one being slightly smaller to provide the inside and the other being slightly larger to provide the outside of a double-thickness tray upon the addition of adhesive medium therebetween; and the like (not shown).

While the above described and/or illustrated embodiments constitute preferred modes of practicing this invention, other embodiments and equivalents may be resorted to within the scope of the actual invention, which is claimed as:

1. Apparatus for producing a stack of nested articles comprising molding means for forming the articles including a first set of plural molding dies, a second set of different plural molding dies, and pulp slurry supply means through which the first and second sets of dies pass during forming of the molded articles, the first set of plural molding dies having anti-jamming steps out of vertical alignment with anti-jamming steps on the second set of plural molding dies, means for supporting the first and second sets of plural molding dies in alternating fashion for shifting motion along a single endless path through said pulp slurry supply means, a mechanical stacker con: structed and arranged to stack molded articles in nested fashion one into the other in the order the articles are delivered to the stacker, article drying means, and means for delivering molded articles from the first and second sets of molding dies to the stacker in the same order the articles are formed whereby the stacker produces a stack with every other article therein having been molded on a die from the first set of molding dies and the remaining articles in the stack having been molded on a die from the second set of molding dies.

2. Apparatus for producing a stack of nested articles as in claim 1 wherein the means for delivering articles to the stacker includes a first set of plural transfer dies for receiving articles from the first set of plural molding dies, a second set of different plural transfer dies for receiving articles from the second set of plural molding dies, and conveyor means adjacent the first and second sets of transfer dies arranged to receive articles therefrom and deliver them to the stacker.

References Cited UNITED STATES PATENTS 3,195,770 7/1965 Robertson 206- K 3,320,120 5/1967 Randall 162--410 X 3,501,083 3/ 1970 Lake 229-45 3,398,049 8/1968 Randall 162-391 X FOREIGN PATENTS 1,060,535 4/1954 France 206-65 K S. LEON BASHORE, Primary Examiner A. DANDREA, In, Assistant Examiner US. Cl. X.R. 

